中国DOS联盟

@echo off
set SrcFile=C:\test\old.txt
set DstFile=C:\test\new.txt

type nul>"%DstFile%"
for /f "tokens=1* delims=:" %%a in ('findstr /n .* "%SrcFile%"') do set var=%%a
set /a var-=1
set row=0
setlocal enabledelayedexpansion
for /f "tokens=1* delims=" %%a in ('findstr .* "%SrcFile%"') do (
  if !row! lss %var% (
  >>"%DstFile%" echo %%a
  )
  set /a row+=1
)
>>"%DstFile%" echo 这是一个笨办法

@echo off
set SrcFile=C:\test 1\old.txt
set DstFile=C:\test 1\new.txt

for /f "usebackq tokens=*" %%a in ("%SrcFile%") do set last=%%a
>"%DstFile%" findstr /ivc:"%last%" "%SrcFile%"
>>"%DstFile%" echo 加上双引号防止路径中有空格